Israel on Tuesday advised its citizens in Egypt's insurgency-hit Sinai Peninsula to leave the region, warning of the threat of an imminent attack.

Israeli holidaymakers are often warned of the risks they face in Sinai, which borders Israel, but the "Level 1" alert issued by the anti-terrorism directorate is its most severe warning.

It described the threat as "very high and concrete."

"The directorate warns of the possibility of attacks against tourist sites in the Sinai area in the immediate term," a statement said.

An Islamist insurgency in the rugged, thinly populated Sinai has gained pace since the military toppled President Mohamed Mursi of the Muslim Brotherhood, Egypt's oldest Islamist movement, in mid-2013 following mass protests against his rule.

Militants have launched a number of deadly cross-border attacks on Israel in the past few years and have occasionally fired rockets across the border into the southern Israeli resort city of Eilat.

The anti-terrorism directorate said that while there was a "constant high threat" in Sinai, Jan. 25, the anniversary of the 2011 revolution in Egypt, was a day that had witnessed attacks in previous years.

Israel and Egypt signed a peace treaty in 1978 and the eastern coast of the peninsula is a popular international tourist destination.